Upgrade Newtonsoft.Json dependency (#311)

Author: xavierdecoster

src/NuGet.Services.KeyVault/NuGet.Services.KeyVault.csproj

@@ -81,6 +81,9 @@
     <PackageReference Include="Microsoft.IdentityModel.Clients.ActiveDirectory">
       <Version>3.19.4</Version>
     </PackageReference>
+    <PackageReference Include="Newtonsoft.Json">
+      <Version>10.0.2</Version>
+    </PackageReference>
     <PackageReference Include="NuGet.Build.Tasks.Pack">
       <Version>4.8.0</Version>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>